Apparatus and method for manufacturing fibrous structures



March 25, 1958 J. DA. CLARK APPARATUS AND METHOD FOR MANUFACTURINGFIBROUS STRUCTURES 2 Sheets-Sheet 1 Filed July 7, 1955 INVENTOR. yamaflfih/zh B) ATTORNEYS.

APPARATUS AND METHOD FOR MANUFACTURING FIBROUS STRUCTURES Filed July 7,.1953 March 25, 1958 J. D'A. CILARK 2 Sheets-Sheet 2 JNVENTOR. I m fiw, ABY 7 Y ATTORNEYS.

19 Gaines. (Q3. Ila-156) This invention relates to the air deposition ofdry fibers in the manufacture of fibrous structures, such as continuousWebs, non-woven fabrics or layers of fibers for use in the production oflaminates, papers, and the like, and it relates more particularly to animprovement in the apparatus and method described and claimed in thecopending application Ser. No. 313,316, filed on October 6, 1952, nowPatent No. 2,720,005.

Briefly described, the method and apparatus of the aforementionedcopending application embodies the use of an elongate cylindricalhousing having a fiber feed opening in the upper end through whichfibers are introduced and which has a forarninous separating wall in thebottom portion through which fibers entrained in streams of aircirculating about the housing are carried through the separating wall insubstantially linear fiow to a foraminous collecting wall which isspaced a short distance below the separating wall. The amount of airdrawn through the collecting wall for purposes of bolding the fibersseparated to form a Web on the surface of the separating wall may begreater than the amount of air which passes with the fibers through theseparating wall so that the deficiency can be made up by a slow infiowof air from the surrounding atmosphere into the space between the wallsin amount insufficient to interfere with the smooth flow of fibers butwhich permits the area between the separating wall and the collectingwall for the first time to be allowed to remain open to the atmospherewithout blowing fibers out into the room and to permit the use ofauxiliary processing elements for treatment of the fibers as they aredeposited on the collecting wall.

The entrainment of separated fibers in the air stream circulating withinthe housing and the subsequent passage of substantially uniformlycontrolled volumes of air and fibers through the openings of theseparating wall to the collecting wall is achieved by an air scrabblerin which streams of air at high velocity are introduced tangentiallyinto the housing to cause the air and the fibers contained therein tocirculate rapidly in one direction about the housing. The circulatingair and entrained fibers of which there is always a large excessavailable, over the face of the separating wall and under positivepressure, creates conditions within the housing similar to that whichexists in a shower head which provides for passage of equal volumes ofair and entrained fibers through each of the openings of the separatingWall for travel to the collecting wall. The amount of air and fiberspassing through the openings of the separating wall are adapted toconstitute a small proportion of the air and fibers circulating withinthe housing thereby to maintain the shower head effect which is believedto be responsible for the uniformity in the volumes of air and fibersand in the distribution of fibers passing through the separating wall.

It has been found that in the use of a fiber depositing head of the airscrabbler type described or of the mechan- 2,827,668 Patented Mar. 25,1953 ical scrabbler type described in the copending applicain thecopending application Ser. No. 61,674, to which this invention is alsoapplicable as an improvement, some of the fibers inevitably becomeentrapped and build up to form clumps on the sides of the housing and onparts not directly being swept by the air streams or mechanical bladesof the scrabblers. Some of these clumps build up on portions of thehousing and the openings of the separating wall While others collect onthe underside of the separating wall where they can break away to formdefects in the fibrous structure.

it is an object of this invention, therefore, to provide an improvementin apparatus of the type described for the deposition of dry fibers inthe manufacture of fibrous structures which Will prevent the aggregationof clumps of fibers in or upon the surfaces of the depositing means andit is a related object to provide apparatus for achieving same.

These and other objects and advantages of this invention willhereinafter appear and for purposes of illustration, but not oflimitation, embodiments of the invention are shown in the accompanyingdrawings in which:

Figure l is a sectional elevational view of a fiber depositing systemembodying features of this invention;

Figure 2 is a sectional elevational view taken substantially along theline 22 of Figure 1;

Figure 3 is a sectional elevational view of a modification in a fiberdepositing head embodying features of this invention, and

Figure 4 is a sectional elevational view of a still further modificationof a fiber depositing head embodying features of this invention.

Referring first to the application of this invention to an air scrabblersystem, in accordance with the practice of this invention, if the air isintroduced tangentially at high velocity as a substantially continuousblade across the cylindrical housing, as defined in application Ser. No.313,316, or in the event that the air is introduced tangentially intothe housing from a plurality of separate inlets or nozzles, at least oneor more air inlets are arranged intermittently to impinge directly butpreferably indirectly upon the surfaces of the housing where fiberbundles might form, such as on the face or on the underside of theseparating wall, as by the introduction of air intermittently in highvelocity streams from one or more of the inlets or preferably where theeffect of such intermittent introduction may be secured more readily bya reciprocating movement of one or more air streams crosswise of thehousing. This intermittent or sweeping action of air streams introducedwithin the housing prevents the aggregation of fibers in the areasanected by the intermittently applied high velocity air streams alsoenhances fiber separation and distribution to the end that a moreuniform concentration of fibers in air is tained and a more desirableproduct free of fiber bundles is produced. The main effect, however, isto sweep the separating wall rapidly with the directly or indirectlaimed jets of air which serve to prevent any appreciable building up offiber bundles inside or outside the separating wall which mightsubsequently be released and fall on the web being formed. Such reactionwith the intermittent streams of air seems to keep the openings of theseparating wall substantially free of blocking fibers with the resultthat the distribution of fibers passing through the openings in theseparating wall and deposited on the collecting wall remains moreuniform and clumps of fibers no longer attempt to form or build up onmicroscopic rough spots on the upper surface of the wall and thetendency for them to form beneath the wall is also greatly reduced. Insome applications it is desirable to place one or more intermittentlyoperating or oscillating the outer surface of the separating wall .freefrom accumulating aggregates or hangers, as illustrated in Figures 3 and4 of the drawings.

. As;shown in the drawings, indicates acylindrical housing-which, inaunit of medium capacity, may be dimensioned from l /2' to 2 feet indiameter and of any desired Width. An inlet openingll is provided acrossthe upper portion of the housing in communication with a feed duct 12into which the fibers 13' are blown or otherwise introduced. Dependinguponthe type of structure that is to be produced, the fibers introducedinto the duct .maybe fibers-which have previously been substantiallycompletely separated into their individual elements or they may be intheform of coarse fibers or aggregates or woody elements of sufiicientlylow specific gravity and size as topermit flotation and entrainment inthe high velocity streams of air circulated within the portion'of thehousing 10. The separating wall may constitute an integral part of thehousing but it is preferred to construct the separating wall as aseparate plate of similarcurvilinear contour which may replaceably besecured in position to seat within the opening across the lower endportion ofthe cylindrical housing so as to adapt the fiberdepositing'head for use with fibers of different character and 'ofdifferent dimensions. The openings 16 in the separating wall may beformed of spaced apertures, as described in the copendingapplication'Ser. No. 61,674, or may constitute spaced slots extendingacross the separating wall and dimensioned to permit passage of fiberstherethrough, as illustrated in the air scrabbler described inapplication Ser. No. 313,3 16. Since certain types of openings arepreferable for use to the atmosphere. This avoidsthe necessity for niprolls or other sealing means which have, heretofore been required inprocesses for the deposition of dry fibers entrained in air. Thisalso'permits the use of auxiliary devices for processing the fibersduring deposition onto the collecting Wall and it also permits thedeposition of one layer of fibers onto another in interfelted relationto prevent delamination, without special. precautions or the like.

Even though conditions relating to a showerhead are maintained with theair or mechanical scrabbler, somefibers invariably become entrappedon'surfaces or edges within the housing or on theface or outer'surfaceof the separating wall. These are not always displaced but tend to buildup into clots or bundles which may ulti- V mately find their way to thecollecting wall to form a defeet in the fibrous structure that isformed. The improvement herein resides in the elimination of suchdifiiculties by a construction whereby, in' an air scrabbler system, oneor more streams of high speed air are introduced tangentiallyinto the"housing or obliquely againstfthe.

can be generated by the oscillating members described" assist in causingthe" desired circulation around the housing and the-crosswisemovement ofthe'air streams pro vides a sweeping action which tends'to equalize.thedistribution of'fibers' in the housing and providea more uniformentrainment of fibers with a corresponding more uniform deposition offibers across the collecting wall.

. The main function of the intermittent or oscillating with one type offibers while openings of another size or collecting wall may be astationary member for use in the manufacture of preformsor it'may beanendless member adapted to travel continuously in one direction tocollect the fibers on the surfaces thereof in the form of a continuousWeb 18 having a thickness depending upon the concentration of fiberspassing through the separating wall and the linear speed of travel ofthe collecting Wall.

Cooperating with the underside of the collecting wall 17 in the areaimmediately beneath that defined by the separating wall 16 is a suctionbox 19 in communication with a fan or other means for withdrawing airthrough the collecting wall to create a suction" which holds theseparated fibers in position on the surface thereof. When, as ispreferred, the volume of air withdrawn through the collecting wall isgreater, by'a small amount, than the volume of air passing with" thefibers through the separating wall, the difference in volume will bemade upby a slight'fiow 'ofair from the surroundingatmospliere into thespace between the separating and collecting 'walls. When the difi'erenceis properly balanced, the

inflow from the surrounding atmosphere is so slight and "gentle as toavoid interference with the linear flow. and

the distribution of fibers during passage from the separating wall tothe collecting wall. At the same time, the slight inflow of air preventsfibers from blowing out into the atmosphereand thus permits the areabetween theseparating wall and the collecting wall to remain openstreamsof'air is to scan directly or indirectly the inside surface'ofthe housing and the foraminous separating wall to prevent theaggregation of clumps of fibers, many of whicb,.and indeed all of thoseclumps formed on the outside of the plate, find their way to thestructure being felted. Someof the advantages of having jets of airoscillating within the housing are that the clumping of fibers isminimized by' breaking up incipient or formed clumps byshearing actioncaused by the impingement ofa' localized high velocity stream of airupon the fiber clamps and which moves through and severs' them, theopenings; in the separating wallremain free of blocking aggregates, andmost important, the build-up of fiber aggregates is' substantiallycompletely eliminated from the inside of the housing and" sometimescompletelyfrom beneath theseparating'wall. In consequence, a more uniform web ,of separated fibers is secured, free of fiber clots andbundles and which thereby provides for an improved fibrous structure:While it is preferred to make use" of oscillatingjets'of thetypedescribed; somewhat comparable results maybesecuredby the use ofstationary jets" set at various angles and preferably set at an angle soas to impinge uponthe' separating wall indirectly and adapted forintermittent operation so as to introduce pulsing jets into thehousingto effect the desired cleansing and other results;

The intermittent or oscillating jets may be joined: with between;Therecipro'cating' nozzle 26 in this modifica tion is positioned at alevel below the stationarynozzles' and cemprises 'an elongate tubing 27,having its inlet end 28 attached to a conduit 29 in communication with asource of air high pressure. The outlet end portion of the tubingextends through the wall of the housing, and is downturned at its end 30to issue the stream of air in a tangential direction. The tubing issupported intermediate its ends in a journal 31 in the form of a bushingsecured to the outer Wall of the housing. Various conventional means maybe provided for effecting turning movement of the tubing to cause thenozzle end portion 30 to reciprocate or rock in a manner to cause thetangential stream of air to sweep crosswise of the housing. One suchmeans, as illustrated, comprises a plate 32 which is fixed about anintermediate portion of the tubing 27 and is engaged at an ofisetportion by one end of a rocker arm. The other end of the rocker arm ispivotally joined to one end of a link 34 which is, in turn, pivotallymounted onto a pin 35 oifset from the center of a disc 36 adapted to belocated so that reciprocating movement will be imparted to the link 34and rocker arm 33 thereby to impart rocking movement of the nozzle 3%}in response to rotation of disc 36.

As previously pointed out, the air inlets may all be positioned at thesame level or at various levels within the housing with some of theinlets directing their streams of air tangentially into the housingwhile the streams issuing from others are radial, some angular, and somereciprocating. It is preferred to balance the air streams so as toprovide for most efiicient operation of the fiber depositing head. Onearrangement wherein the inlets are located at a uniform level and spacedcrosswise of the housing is illustrated in Figure 4- wherein the nozzlesare stationarily fixed in various angular positions. One suitablearrangement in a housing about 2 feet wide makes use of nine inlets infixed angular position across the housing. The first, fifth and ninth,represented by the numeral 49, are arranged to introduce the air streamstangentially within the housing. The third and seventh, represented bythe numeral 41, may be positioned to direct the streams of airsubstantially radially into the housing so as better to disintegrate thecirculating clumps of fibers by applying blasts perpendicular to theirmovement. The second, fourth, sixth and eighth, represented by thenumeral 42, are positioned at various angles therebetween and areadapted by suitable controls to introduce their streams of airintermittently into the housing to provide intermittent jets whichimpart a type of displacing action to prevent the accumulation of fiberson various surfaces within and without the housing.

Instead of mounting the inlets 42 in fixed position for introducing jetsof air intermittently into the housing, such inlets may be adapted forreciprocating movement 42 as previously described, continuously tointroduce the air streams into the housing at various angles which sweepacross the surfaces Within the housing and are preferably directed toengage the housing just prior to the face of the separating Wall tomaintain the surfaces thereof substantially free of clinging or cloggingfibers without afiecting the fibers deposited on the collectingwallbeneath.

The fiber agglomerates have also been found to form on the underside ofthe separating wall where they are able to fall with the fibers passingthrough the separating wall and form blemishes in the structure that isformed on the collecting wail. While this accumulation of fibers oncertain points on outer surfaces of the separating wall will be reducedmaterially in response to the intermittent indirect action of jets uponthe inner interior surfaces of the separating wall, it may be expedientto avoid such possibilities for blemishes and interference with fiberdeposition substantially completely by the use of similar jets operatingexterior of the housing to impinge tangentially upon the exterior sideof the separating Wall preferably synchronized in its movements withjets operating intermittently or oscillating within the housing toenable increased blow with less disturbance of fiber flow.

As inthe system previously described, the jet or jets or air may issuefrom stationary nozzles 44 with narrow bores spaced laterally across thehousing in spaced relation with the underside thereof but positioned todirect the air streams at high velocity intermittently across thesurface of the separating Wall so as to sweep the surface for theremoval of fibers which might cling thereto and form incipient clumps. Asystem of this character is illustrated in Figure 4 of the drawings.

Instead, one or more nozzles as, adapted for reciprocation as previouslydescribed, may be positioned in spaced relation with the underside ofthe housing for sweeping the underside of the separating wall with ahigh velocity stream of air as the nozzle is reciprocated. Fiberaccumulation Will be minimized by reaction wiLh the air streamintermittently sweeping across the surfaces of the wall Without the needfor so much air as might interfere with the flow of fibers and air inuniform volume and in the desired distribution in normal operation fromthe separating wall to the collecting wall.

A system based upon reciprocating nozzles Within and without the housingis shown in Figure 3 of the drawings. Reciprocation to direct the airstream laterally across the housing may be achieved by means Within theskill of the art, as illustrated by the means shown in Figure 1.

It will be apparent from the description that the reciprocal movement ofsome of the streams of air crosswise of the housing provides forimproved operation in the development of a better distribution of fibersin the air stream and more rapid and uniform transfer of fibers from thefiber depositing head onto the collecting wall in the manufacture offibrous structures. The intermittent action of the induced localized hih velocity air streams upon the separating wall serves to keep itrelatively free from aggregates both on the ingoing and outgoingsurfaces and thus avoid the serious problem of build-ups and releases ofclots of fibers which constitute a severe draw-back to the satisfactoryoperation of all kinds of equipment adapted to deposit fibers by way ofan air stream.

By the use of nozzles having openings of small dimension, a much higherair velocity and thus a greater cleansing eifect may be hadinstantaneously over localized areas of the separating Wall with a givenvolume of free air than could otherwise be tolerated withoutinterference or effect on the uniformity of distribution and depositionof fibers to form the web. Moreover, the crosswise movement of the jetsacross the surfaces of the housing serves very effectively to dislodgeaggregates which might otherwise be pinned down by the blasts from fixedor non-interrupted jets.

It will be obvious that this invention may be adapted for use with othertypes of fiber felting heads through which fibers are transported to belaid down into a structure such as by providing suitable means tointermittently impinge jets of high velocity air across surfaces uponvwhich fibers may aggregate and from which such aggregates might fall orbe carried to the structure to cause blemishes therein.

t will be understood that changes may be made in d tails ofconstruction, arrangement and operation, and in the arrangement of airnozzles for the processes described without departing from the spirit ofthe invention, especially as defined in the following claims.

I claim:

1. In apparatus for the air deposition of dry fibers in the manufactureof a fibrous structure comprising a felting head having an inlet in oneportion through which fibers are fed into the head and an outlet inanother portion in the form of a foraminous separating wall throughwhich fibers are able to pass, a collecting wall spaced a short distancefrom the separating wall having forarnens therein dimensioned to preventpassage of fibers, means for feeding dry fibers into the felting head,air nozzles in the felting head through which streams of air at high.manufacture of fibrous structures comprising a felting velocity aredirected into-the; head; and meansfor. rocking some of. said nozzlescrosswise ofthe head. whereby the: streams. of air are caused to sweepacross thezhead: to -free fibers entrapped onthe surfaces thereof.

2. Apparatus for the air deposition of dry fibers in the manufacture offibrous structuresxcompri'sing a felting head in the form of acylindrical housinghaving an inlet, in one wall portion through. whichfibe'rss are fed into thehousing, an outlet in another Wall portion in Vthe form of a foraminous separating wall throughwhich the foramens ofthe separating wall'free from aggre- 3. Apparatus for the air depositionof dry fibers in the manufacture of fibrous structure's comprising afeltinghead in the form of a housing having-an inlet in one portionthrough which. fibers are fed into the housing, an outlet in anotherportion which forms a foraminous separating Wall through which fibers'are able to pass and a collecting. Wall spaced a short distance fromthe separating wall having foramens therein dimensioned .topreventpassage of fibers, means for feeding dry fibers through the inlet intothe housing, a plurality of air nozzles'arranged crosswise of thehousing through which streams of air at high velocity are directed intothe houscome entrained in the air stream-in: uniform distribution ing,some of said nozzles being positioned todirect their 7 air streamstangentially into the housing to cause the air and fibers entrainedtherein to circulate rapidly about the housing, and means for causingair streams issuing from some of said nozzles intermittently to engagethe surface of the housing whereby the surfaces and the fora- 'mens oftheseparating wall are kept free from aggregates of fibers.

wise of the housing to free fibers entrapped on the sur faces thereof.

5. Apparatus as claimed in claim 3 in which the means for causing'airstreams issuing from some of said nozzlesintermittently to engage thesurfaces of said hous- 7 ing comprises means for intermittentlyintroducing streams of air through some of said nozzles within thehousing. a

6 Apparatus as claimed in claim a in which said streams of airintermittently engaging the surfaces ofthe housing comprise fine streamsof air'of higher velocity than issue from the remainder of the airnozzles so as not-3m interfere with the circulating movements of the airand fibers about the housing and'their'passage through thes'eparatingwall to the collecting wall.

7. Apparatus for the 'depositionof dry fibers in the 8 7 head: includinga. cylindricali housing: having an inlet: in one portion throughrwhichfibersarefedintothe housing, an outlet' in. another portion which: formsaforarn-q inousl separating; wallthr'ough. whichfibersl are abletovpass, and includes: a. collectingwall. spaced ashort; distance fromtheseparating'wallhaving foramens therein dimensionedfto preventpassage.-of.fibers;.means for. feeding: dry fibers; through theinletintov the housing,- a plurality of inlets through which streams of. airatv high velocity aredirected into the housing,v some. of the airinlets. being positioned to direct their-streamsof air tangentiallyintorthe. housing; others-of said air inlets'being;

positioned to direct their streams radially intothe housing, while stillothers are positionedito direct their streams at'angles between radialand tangential, and means for rocking someof said air'inle'ts'.crosswiseof the housing other than those which are positioned. to directtheir streams of: air radially into the housing to. C3l1$ ilil6 streams.of air issuing therefromtosweep across thesur faces of" the; housing.whereby the surfaces and the foramens of the separating wall are keptfre'e'from aggregatesof fibers; whereby the fiberswithin. thehousingbeand in' substantial separation for. passage with the airthrough the. separating wall to. the collecting wall.

8. Apparatus as claimed in claim 3 which includes air" inlets positionedexteriorly of the housing and; at an angle. todirect the streams of airissuing therefrom onto the separatingwa'll, andimeans for causing theairstreams issuing therefrom intermittently to 'engagefportionsl oftheseparating'wa'll to freenthe surfaces from agglomerates of. fiberswhichmight collect thereon.

9. In themanufacture of fibrous structures by: the deposition of fibrouselements entrained in an air stream wherein. the air' stream andentrained'fibers are passed through a felting head having aforaminouswall through V which air and entrained fibers are able topass, the im-' provement which comprises intermittently sweeping'theinterior of the felting head with a jet of high velocity'airdirected intothe stream ofair entrained fibers circulating aboutthezfelting head to' prevent the aggregation of fibers onto. thesurfaces thereof, and sweeping the exterior ofthe' foraminous wallthrough which the fibers pass with a fine jet of high velocity airdirected substantially toward said wall.

. 10. In the deposition of dry fibersentrained in an-air i streamwherein the air stream and entrained fibers are passed through a feltinghead through openings toa collectingmember in the formation of a fibrousstructure,

the method of subjecting at least some of the surfaces of the head 'tothe effect of the intermittent application of jets of. high velocity airseparate and apart fron'rthe' air stream entraining the-fibers forpreventing the aggregation'of fibers on the interiorsurface of thefelting head acted upon by the jets and the openings-leading to thecollecting member;

References Cited in the file of thispaten t UNITED STATES PATENTS Clarket a1. o r. 11, 1955

10. IN THE DEPOSITION OF DRY FIBERS ENTRAINED IN AN AIR STREAM WHEREINTHE AIR STREAM AND ENTRAINED FIBERS ARE PASSED THROUGH A FELTING HEADTHROUGH OPENINGS TO A COLLECTING MEMBER IN THE FORMATION OF A FIBROUSSTRUCTURE, THE METHOD OF SUBJECTING AT LEAST SOME OF THE SURFACES OF THEHEAD TO THE EFFECT OF THE INTERMITTENT APPLICATION OF JETS OF HIGHVELOCITY AIR SEPARATE AND APART FROM THE AIR STREAM ENTRAINING THEFIBERS FOR PREVENTING THE AGGREGATION OF FIBERS ON THE INTERIOR SURFACEOF THE FELTING HEAD ACTED UPOM BY THE JETS AND THE OPENINGS LEADING TOTHE COLLECTING MEMBER.